Almost all of the characters are loveable in One Piece. The story revolves around Luffy traveling from island to island as he makes new friends to find One Piece. This adventure is generally funny, sometimes sad, but enjoyable in overall. However, as I stated before, the crappy animation totally ruined this anime(at least last 200 episodes), but you can still read manga tough.
If in future, some good animation company summarize the whole story to 200 epsiodes or so with great animation, this will be one of the best animes without doubt. But, currently, I do not suggest watching this to anyone.
